METHOD FOR REPORTING A CHANNEL QUALITY INFORMATION IN WIRELESS COMMUNICATION SYSTEM
Provided is a method of reporting channel quality information in a wireless communication system. A relay station (RS) measures an uplink signal of a mobile station (MS) to obtain a measurement result, and transmits a report message including the measurement result and identification information of the MS to a base station (BS).
The present invention relates to a wireless communication system, and more particularly, to a method of reporting uplink channel quality information of a mobile station (MS) to a base station (BS) in a relay station (RS).
The present invention is derived from research conducted as a part of “IT New Growing Engine Core Technology Development Projects” promoted by the Ministry of Information and Communication and the Institute for Information Technology Advancement, Republic of Korea [Research Title: WiBro Evolution Standardization].
BACKGROUND ARTMobile communication systems suffer from many problems due to a change in a wireless channel that is used to transmit data to mobile terminals. A wireless channel between a transmitter and a receiver changes when a terminal is moved, a frequency band changes, environmental conditions, such as weather conditions or geographic features, change, and so on.
The Institute of Electrical and Electronics Engineers (IEEE) 802.16 Working Group (WG) recommends practices to support the development and deployment of broadband wireless access (BWA) standards, and the IEEE 802.16-2004 standard and IEEE 8 02.16e-2005 standard, which improves upon the IEEE 802.16-2004 standard by adding support for mobility, have been published. The WiMAX forum actively develops both the IEEE 802.16-2004 and IEEE 802.16e-2005 standards and promotes the introduction of broadband wireless access services. The forum addresses not only a wireless standard but also a network standard.
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According to the BWA standard, the BS 100 allocates wireless resources and controls a procedure for each user in a cell, and the SS or MS 120 transmits a message and data using the resources allocated by the BS 100. The BS 100 broadcasts a MAP control message to indicate the allocated resources for each frame, and the SS or the MS 120 recognizes the allocated resources using downlink (DL) frame information and uplink (UL) frame information included in the broadcast MAP control message. The SS or the MS 120 transmits a media access control (MAC)-protocol data unit (PDU) using the allocated resources.
Currently, IEEE 802.16 suggests a standard for the RS 110 which relays a signal between the BS 100 and the MS 120. A DL refers to the transmission of a signal from the BS 100 to the MS 120 via the RS 110. A UL refers to the transmission of a signal from the MS 120 to the BS 100 via the RS 110.
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An IEEE 802.16j system including an MS that is compatible with the 16 standard has a problem in that since the MS recognizes only a BS but fails to recognize an additional RS, the MS cannot transmit RS related information to an RS or the BS.
When an MS is moved in a cell of a BS, a plurality of RSs may be located between the BS and the MS. Each of the RSs transmits a signal transmitted by the MS to the BS, and transmits a signal transmitted by the BS or an RS to the MS. Since a wireless channel between the moving MS and the RS changes, the BS allocating wireless resources must always collect information on the changing wireless channel. The BS makes a schedule to determine a modulation and coding scheme (MCS) level and a resource size by using the collected information on the wireless channel.
DETAILED DESCRIPTION OF THE INVENTION Technical ProblemThe present invention provides a method of measuring and reporting an uplink signal of a mobile station (MS) to a base station (BS) in a wireless communication system and a message format used in the reporting method.
Technical SolutionAccording to an aspect of the present invention, there is provided a method of reporting channel quality in a relay station of a wireless communication system, the method comprising: measuring the quality of an uplink between the relay station and a mobile station; and transmitting a report message including a measurement result and identification information of the relay station to a base station.
According to another aspect of the present invention, there is provided a method of reporting channel quality in a base station of a wireless communication system, the method comprising: receiving from a relay station a report message including quality measurement information of an uplink between the relay station and a mobile station and identification information of the relay station; and selecting a new relay station on the basis of the report message.
According to another aspect of the present invention, there is provided a computer-readable recording medium having embodied thereon a message format for reporting channel quality in a wireless communication system, the computer-readable recording medium comprising: a first identification information field including identification information of a mobile station connected to a relay station; and a channel quality field including information on channel quality measured in regard to an uplink of the mobile station.
ADVANTAGEOUS EFFECTSAccording to the present invention, since an additional control process for transmitting mobile station (MS) information between a relay station (RS), which measures an MS uplink signal, and a base station (BS), which manages MS information, is not necessary, resources can be saved. When the RS reports an MS measurement result, the amount of data reported after filtering can be reduced. A plurality of filtering thresholds can be set and modulation and coding scheme (MCS) levels can be respectively applied to the filtering thresholds.
According to an aspect of the present invention, there is provided a method of reporting channel quality in a relay station (RS) of a wireless communication system, the method comprising:measuring the quality of an uplink between the RS and a mobile station (MS); and transmitting a report message including a measurement result and identification information of the RS to a base station (BS).
According to another aspect of the present invention, there is provided an RS of a wireless communication system, the RS comprising: a quality measuring unit measuring the quality of an uplink between the RS and an MS to obtain measurement information; and a message transmitting unit transmitting a report message including the measurement information and identification information of the MS to a BS.
According to another aspect of the present invention, there is provided a computer-readable recording medium having embodied thereon a message format for reporting channel quality in a wireless communication system, the computer-readable recording medium comprising: a first identification information field including identification information of an MS connected to an RS; and a channel quality field including information on channel quality measured in regard to an uplink of the MS.
MODE OF THE INVENTIONThe present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown.
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For example, it is assumed that a CQICH is measured. Once the MS 220 is allocated the CQICH from the BS 200, the MS 220 transmits a downlink wireless channel measurement result. The RS 210 measures the strength of the downlink wireless channel measurement result received from the MS 220, and reports a measurement result to the BS 200. Hence, by using the CQICH, the BS 200 or the RS 210 can make the MS 220 transmit the channel measurement result at a desired point of time. In detail, once the BS 200 allocates the CQICH to the MS 220 using an UL-MAP, the MS 220 following the 16 standard transmits a measurement result of the allocated CQICH to the RS 210. The RS 210 receiving the measurement result of the CQICH from the MS 220 can determine the strength of the received measurement result. Since the same CQICH is transmitted by the MS 220, an RS 210 determining the highest strength is assumed to have the best wireless channel between the MS 220 and the RS 210.
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In operation S370, the RS 310 receives a signal, for example, unicast data, from the recognized MS 320. In operation S380, the RS 310 measures the quality of the signal received from the MS 320. In operation S390, the RS 310 transmits a measurement result to the BS 300 if the measurement result corresponds to a preset threshold. A filtering process for determining whether the measurement result corresponds to the preset threshold will be explained later in detail with reference to
When transmitting measurement information to a BS, an RS transmits only information required by the BS by filtering, thereby minimizing wireless resource allocation. That is, since the BS changes wireless channel resources using the measurement information transmitted by the RS, the RS transmits only information necessary for determining whether to change the wireless channel resources to the BS.
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If the uplink signal measurement result of the MS is higher than the MS detection threshold 600, the RS reports the measurement result to the BS. The fact that the measurement result is higher than the MS detection threshold 600 means that the RS can receive a signal, whereas the fact that the measurement result is lower than the MS detection threshold 600 means that the RS cannot receive a signal. Accordingly, if the uplink signal measurement result of a specific MS and a previous measurement result belong to different regions on the basis of the MS detection threshold, the RS reports the uplink signal measurement result to the BS.
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In addition, the RS 910 may analyze control messages exchanged between the BS 900 and the MS 920 and change the MS information. For example, the RS 910 obtains MS message added to a ranging response (RNG-RSP) message, and obtains MS information erased from a de/re-register command (DREG-CMD) message. Also, the RS 910 analyzes messages related to a handover procedure and thus obtains MS information of an MS moved to another cell.
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In addition, the measurement report message of
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The present invention may be embodied as computer readable codes on a computer readable recording medium. The computer readable recording medium is any data storage device that can store data which can be thereafter read by a computer system. Examples of the computer readable recording medium include read-only memories (ROMs), random-access memories (RAMs), CD-ROMs, magnetic tapes, floppy disks, and optical data storage devices. The computer readable recording medium can be dispersively installed in a computer system connected to a network, and stored and executed as a computer readable code in a distributed computing environment.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. The preferred embodiments should be considered in a descriptive sense only and not for purposes of limitation. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present invention.
Claims
1. A method of reporting channel quality in a relay station of a wireless communication system, the method comprising:
- measuring the quality of an uplink between the relay station and a mobile station; and
- transmitting a report message including a measurement result and identification information of the relay station to a base station.
2. The method of claim 1, wherein the measuring of the quality comprises measuring the quality of an uplink between two or more mobile stations connected to the relay station,
- wherein the transmitting of the report message comprises transmitting a report message including identification information of the relay station, identification information of the two or more mobile stations, and measurement information of the uplink between the two or more mobile stations.
3. The method of claim 1, wherein the measuring of the quality comprises measuring at least one of a received signal strength indicator (RSSI), a carrier to interference and noise ratio (CINR), and a timing adjust value with respect to the uplink.
4. The method of claim 1, further comprising receiving a transmission request of the report message from the base station.
5. The method of claim 1, wherein the transmitting of the report message comprises transmitting the report message if the measurement result is higher than a preset threshold.
6. The method of claim 1, wherein the transmitting of the report message comprises transmitting the report message if the measurement result does not belong to a region, to which a previous measurement result belongs, among regions divided by a plurality of preset thresholds.
7. The method of claim 1, wherein the transmitting of the report message comprises transmitting the report message if a difference between the measurement result and a previous measurement result is higher than a predetermined value.
8. A method of reporting channel quality in a base station of a wireless communication system, the method comprising:
- receiving from a relay station a report message including quality measurement in formation of an uplink between the relay station and a mobile station and identification information of the relay station; and
- selecting a new relay station on the basis of the report message.
9. The method of claim 8, wherein the report message includes identification information of the relay station, identification information of two or more mobile stations connected to the relay station, and quality measurement information of an uplink between the two or more mobile stations.
10. The method of claim 8, further comprising requesting a transmission of the report message to the relay station.
11. The method of claim 8, further comprising updating resource allocation to the mobile station on the basis of the report message.
12. A computer-readable recording medium having embodied thereon a message format for reporting channel quality in a wireless communication system, the computer-readable recording medium comprising:
- a first identification information field including identification information of a mobile station connected to a relay station; and
- a channel quality field including information on channel quality measured on an uplink of the mobile station.
13. The computer-readable recording medium of claim 12, further comprising a second identification information field including identification information of the relay station.
14. The computer-readable recording medium of claim 12, wherein the channel quality field includes at least one of an RSSI, a CINR, and a timing adjust value with respect to the uplink.
Type: Application
Filed: Oct 29, 2007
Publication Date: Mar 25, 2010
Inventors: Sung-Cheol Chang (Daejeon-city), Min-Sik Seo (Daejeon-city), Chul-Sik Yoon (Seoul)
Application Number: 12/447,422
International Classification: H04W 24/00 (20090101); H04W 72/08 (20090101); H04B 17/02 (20060101);